Nuggihalli schist belt in the Karnataka Craton; an Archean layered complex as interpreted from chromite distribution

1983 ◽  
Vol 78 (3) ◽  
pp. 507-513 ◽  
Author(s):  
Revanna Nijagunappa ◽  
Channappa Naganna
Keyword(s):  
Schist Belt ◽  
Layered Complex

scholarly journals Petrography of Bethampudi Anorthosites Layered Complex from the Khammam Schist Belt, Telangana, India

2016 ◽  
Vol 06 (11) ◽  
pp. 1434-1456
Author(s):  
Thallapalli Brahmaiah ◽  
Chinthala Ravi ◽  
Kandukuri Sai Krishna ◽  
Gugulothu Papanna ◽  
Katta Satya Sai Prasad
Keyword(s):  
Schist Belt ◽  
Layered Complex

THE HIGH-TI CAMP FREETOWN LAYERED COMPLEX (SIERRA LEONE) - LITHOSPHERIC IMPRINTING REVEALED BY ISOTOPE SYSTEMATICS

2017 ◽  
Author(s):  
Sara Callegaro ◽  
◽  
Andrea Marzoli ◽  
Hervé Bertrand ◽  
Janne Blichert-Toft ◽  
...  
Keyword(s):  
Sierra Leone ◽  
Isotope Systematics ◽  
Layered Complex

scholarly journals Tamuraite, Ir5Fe10S16, a New Species of Platinum-Group Mineral from the Sisim Placer Zone, Eastern Sayans, Russia

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 545
Author(s):  
Andrei Y. Barkov ◽  
Nadezhda D. Tolstykh ◽  
Robert F. Martin ◽  
Andrew M. McDonald
Keyword(s):  
National Laboratory ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Cell Parameters ◽  
Reflected Light ◽  
Platinum Group Minerals ◽  
Platinum Group ◽  
Probable Space ◽  
Layered Complex ◽  
Residual Melt

Tamuraite, ideally Ir5Fe10S16, occurs as discrete phases (≤20 μm) in composite inclusions hosted by grains of osmium (≤0.5 mm across) rich in Ir, in association with other platinum-group minerals in the River Ko deposit of the Sisim Placer Zone, southern Krasnoyarskiy Kray, Russia. In droplet-like inclusions, tamuraite is typically intergrown with Rh-rich pentlandite and Ir-bearing members of the laurite–erlichmanite series (up to ~20 mol.% “IrS2”). Tamuraite is gray to brownish gray in reflected light. It is opaque, with a metallic luster. Its bireflectance is very weak to absent. It is nonpleochroic to slightly pleochroic (grayish to light brown tints). It appears to be very weakly anisotropic. The calculated density is 6.30 g·cm−3. The results of six WDS analyses are Ir 29.30 (27.75–30.68), Rh 9.57 (8.46–10.71), Pt 1.85 (1.43–2.10), Ru 0.05 (0.02–0.07), Os 0.06 (0.03–0.13), Fe 13.09 (12.38–13.74), Ni 12.18 (11.78–13.12), Cu 6.30 (6.06–6.56), Co 0.06 (0.04–0.07), S 27.23 (26.14–27.89), for a total of 99.69 wt %. This composition corresponds to (Ir2.87Rh1.75Pt0.18Ru0.01Os0.01)Σ4.82(Fe4.41Ni3.90Cu1.87Co0.02)Σ10.20S15.98, calculated based on a total of 31 atoms per formula unit. The general formula is (Ir,Rh)5(Fe,Ni,Cu)10S16. Results of synchrotron micro-Laue diffraction studies indicate that tamuraite is trigonal. Its probable space group is R–3m (#166), and the unit-cell parameters are a = 7.073(1) Å, c = 34.277(8) Å, V = 1485(1) Å3, and Z = 3. The c:a ratio is 4.8462. The strongest eight peaks in the X-ray diffraction pattern [d in Å(hkl)(I)] are: 3.0106(26)(100), 1.7699(40)(71), 1.7583(2016)(65), 2.7994(205)(56), 2.9963(1010)(50), 5.7740(10)(45), 3.0534(20)(43) and 2.4948(208)(38). The crystal structure is derivative of pentlandite and related to that of oberthürite and torryweiserite. Tamuraite crystallized from a residual melt enriched in S, Fe, Ni, Cu, and Rh; these elements were incompatible in the Os–Ir alloy that nucleated in lode zones of chromitites in the Lysanskiy layered complex, Eastern Sayans, Russia. The name honors Nobumichi Tamura, senior scientist at the Advanced Light Source of the Lawrence Berkeley National Laboratory, Berkeley, California.

Identifying geochemical anomalies and spatial distribution of gold and associated elements in the Zuru Schist Belt, northwest Nigeria

2021 ◽  
Vol 14 (6) ◽  
Author(s):  
Babatunde Joseph Fagbohun ◽  
Oluseyi Adunola Bamisaiye ◽  
Femi Joshua Ayoola ◽  
Ayotunde Allen Omitogun ◽  
Blessing Adeoti
Keyword(s):  
Spatial Distribution ◽  
Schist Belt ◽  
Geochemical Anomalies

Eudialyte-group minerals in rocks of Lovozero layered complex at Mt. Karnasurt and Mt. Kedykvyrpakhk

2015 ◽  
Vol 57 (7) ◽  
pp. 600-613 ◽  
Author(s):  
G. Yu. Ivanyuk ◽  
Ya. A. Pakhomovsky ◽  
V. N. Yakovenchuk
Keyword(s):  
Eudialyte Group ◽  
Layered Complex

The Mesoarchean Amikoq Layered Complex of SW Greenland: Part 2. Geochemical evidence for high-Mg noritic plutonism through crustal assimilation

2021 ◽  
pp. 1-64
Author(s):  
Emil Aarestrup ◽  
Iain McDonald ◽  
Paul E.B. Armitage ◽  
Allen P. Nutman ◽  
Ole Christiansen ◽  
...  
Keyword(s):  
Crustal Assimilation ◽  
Geochemical Evidence ◽  
Layered Complex

scholarly journals Geochemical Characteristics and Tectonic Setting of Amphibolites in Ifewara Area, Ife-Ilesha Schist Belt, Southwestern Nigeria

2016 ◽  
Vol 6 (1) ◽  
pp. 43 ◽  
Author(s):  
Anthony Temidayo Bolarinwa ◽  
Adebimpe Atinuke Adepoju
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Major Element ◽  
Tectonic Setting ◽  
Crustal Contamination ◽  
Geochemical Evolution ◽  
Schist Belt ◽  
Southwestern Nigeria ◽  
Eu Anomaly ◽  
Ree Patterns

Trace and Rare Earth Elements (REEs) data are used to constrain the geochemical evolution of the amphibolites from Ifewara in the Ife-Ilesha schist belt of southwestern Nigeria. The amphibolites can be grouped into banded and sheared amphibolites. Major element data show SiO2 (48.34%), Fe2O3 (11.03-17.88%), MgO (5.76-9.90%), CaO (7.76-18.6%) and TiO2 (0.44-1.77%) contents which are similar to amphibolites in other schist belts in Nigeria. The Al2O3 (2.85-15.55%) content is varied, with the higher values suggesting alkali basalt protolith. Trace and rare earth elements composition reveal Sr (160-1077ppm), Rb (0.5-22.9ppm), Ni (4.7-10.2ppm), Co (12.2-50.9 ppm) and Cr (2-7ppm). Chondrite-normalized REE patterns show that the banded amphibolites have HREE depletion and both negative and positive Eu anomalies while the sheared variety showed slight LREE enrichment with no apparent Eu anomaly. The study amphibolites plot in the Mid Oceanic Ridge Basalts (MORB) and within plate basalt fields on the Zr/Y vs Zr discriminatory diagrams. They are further classified as volcanic arc basalt and E-type MORB on the Th- Hf/3- Ta and the Zr-Nb-Y diagrams. The amphibolites precursor is considered a tholeiitic suite that suffered crustal contamination, during emplacement in a rifted crust.

Coupled substitutions in PGE-enriched cobaltite: new evidence from the Rio Jacaré layered complex, Bahia state, Brazil

2015 ◽  
Vol 79 (5) ◽  
pp. 1185-1193 ◽  
Author(s):  
Andrei Y. Barkov ◽  
Yana Fedortchouk ◽  
Robert A. Campbell ◽  
Tapio A.A. Halkoaho
Keyword(s):  
Layered Intrusion ◽  
Fluid Phase ◽  
Primary Phase ◽  
Sulfur Fugacity ◽  
Type Molecule ◽  
Substitution Mechanism ◽  
Compositional Variability ◽  
New Evidence ◽  
Layered Complex ◽  
Grain Core

AbstractMicrocrystals of platinum-group element (PGE)-bearing cobaltite occur in the Gulcari A deposit of vanadiferous titanomagnetite in the lower zone of the Rio Jacaré mafic-ultramafic layered intrusion, Brazil. Aggregates of cobaltite and sperrylite are cluster-like and developed generally along the boundary of Fe-Ti oxide grains with deuteric silicates. Our observations of cryptic zoning, compositional variability and interelement correlations are based on 37 analytical points (wavelength-dispersion spectrometry mode) of cobaltite, and indicate that Ir and Rh behave uniformly with Ni and antipathetically with Co which, in turn, correlates directly with S content. Iridium, Rh and Ni apparently substitute for Co in the As-enriched grain core, and the substitution mechanism invokes solid solution with a cattierite-type molecule: (Ni + Ir + Rh) + (AsS) = Co + (S2). The PGE-bearing cobaltite probably crystallized as a primary phase at 500 to 300°C, from microvolumes of a late fluid phase. The observed enrichment in S and decrease in the As:S ratio at the cobaltite grain margins is a reflection of the increase in sulfur fugacity (fS2) with decrease in temperature of crystallization.

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